Database management systems (“DBMS”) are increasingly expected to perform at high levels of reliability, performance, and efficiency on a growing range of platforms, from server-class installations to mobile devices. Such platforms are diverse and varied in terms of available resources and capabilities, such as computing power and available memory. Query optimization is an important process, whose resource consumption and performance may depend on several factors. Query optimizers may need to adapt to the highly diverse environments of the platforms and environments on which DBMSs execute, such as platforms and environments characterized by mixed workloads and limited correlation between query complexity, execution time, and database size.
In the drawings, like reference numbers generally indicate identical or similar elements. Additionally, generally, the left-most digit(s) of a reference number identifies the drawing in which the reference number first appears.